Indeed, as we search for life on other planets, we've used the Earth as our standard reference. Practically speaking, it's the only model we've got — and it appears to be a pretty damned good one; Earth has been teeming with life for billions of years and, quite importantly, it's even spawned a radio-capable, space-faring civilization.
That being said, what makes us so sure it's the best model for habitability? Could other planets or moons be even more suitable for life? A pair of astrobiologists say yes. To find a habitable and ultimately an inhabited world, they argue we should adopt a biocentric approach rather than a geo- or anthropocentric one.

"We have found a habitable environment," said John Grotzinger, project scientist for the Curiosity mission. "The water that was here was so benign and supportive of life that if a human had been on the planet back then, they could drink it."